Acute kidney injury in the intensive care unit: current trends in incidence and outcome

Acute kidney injury (AKI) is a common clinical problem with significant clinical and economic consequences. A number of studies point to a rising incidence of AKI in the hospital and in the intensive care unit over the past several years, and an increase in the degree of co-morbidity associated with it. Recent evidence suggests that there has been some improvement in outcomes over time. Nevertheless, the mortality associated with AKI remains unacceptably high, and further work is needed. Recently developed consensus definitions will be useful in this regard

Heart-Kidney Interaction: Epidemiology of Cardiorenal Syndromes

Cardiac and kidney diseases are common, increasingly encountered, and often coexist. Recently, the Acute Dialysis Quality Initiative (ADQI) Working Group convened a consensus conference to develop a classification scheme for the CRS and for five discrete subtypes. These CRS subtypes likely share pathophysiologic mechanisms, however, also have distinguishing clinical features, in terms of precipitating events, risk identification, natural history, and outcomes. Knowledge of the epidemiology of heart-kidney interaction stratified by the proposed CRS subtypes is increasingly important for understanding the overall burden of disease for each CRS subtype, along with associated morbidity, mortality, and health resource utilization. Likewise, an understanding of the epidemiology of CRS is necessary for characterizing whether there exists important knowledge gaps and to aid in the design of clinical studies. This paper will provide a summary of the epidemiology of the cardiorenal syndrome and its subtypes

Early Diagnosis of Acute Kidney Injury: The Promise of Novel Biomarkers

The incidence of acute kidney injury (AKI) formerly referred to as acute renal failure (ARF) is increasing to epidemic proportions. Development of AKI portends excessive morbidity and mortality. AKI is associated with prolonged hospital stay, increased healthcare costs and high mortality especially in critically ill patients. The mortality rate has remained largely unchanged for many decades. Delay in the diagnosis of AKI using conventional biomarkers like urine output and serum creatinine has been one of the important obstacles in applying effective early interventions. Several new biomarkers are being evaluated in a quest for early diagnosis of AKI, among which neutrophil gelatinase-associated lipocalin (NGAL) appears to be one of the most promising. This review summarizes the recent literature on these biomarkers

A proposed algorithm for initiation of renal replacement therapy in adult critically ill patients

Critically ill patients whose course is complicated by acute kidney injury often receive renal replacement therapy (RRT). For these patients, initiation of RRT results in a considerable escalation in both the complexity and associated cost of care. While RRT is extensively used in clinical practice, there remains uncertainty about the ideal circumstances of when to initiate RRT and for what indications. The process of deciding when to initiate RRT in critically ill patients is complex and is influenced by numerous factors, including patient-specific and clinician-specific factors and those related to local organizational/logistical issues. Studies have shown marked variation between clinicians, and across institutions and countries. As a consequence, analysis of ideal circumstances under which to initiate RRT is challenging. Recognizing this limitation, we review the available data and propose a clinical algorithm to aid in the decision for RRT initiation in critically ill adult patients. The algorithm incorporates several patient-specific factors, based on evidence when available, that may decisively influence when to initiate RRT. The objective of this algorithm is to provide a starting point to guide clinicians on when to initiate RRT in critically ill adult patients. In addition, the proposed algorithm is intended to provide a foundation for prospective evaluation and the development of a broad consensus on when to initiate RRT in critically ill patients

Erratum to: Epidemiology and outcome of the cardio-renal syndrome

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ADPKD: Prototype of Cardiorenal Syndrome Type 4

The cardiorenal syndrome type 4 (Chronic Renocardiac Syndrome) is characterized by a condition of primary chronic kidney disease (CKD) that leads to an impairment of the cardiac function, ventricular hypertrophy, diastolic dysfunction, and/or increased risk of adverse cardiovascular events. Clinically, it is very difficult to distinguish between CRS type 2 (Chronic Cardiorenal Syndrome) and CRS type 4 (Chronic Renocardiac Syndrome) because often it is not clear whether the primary cause of the syndrome depends on the heart or the kidney. Autosomal dominant polycystic kidney disease (ADPKD), a genetic disease that causes CKD, could be viewed as an ideal prototype of CRS type 4 because it is certain that the primary cause of cardiorenal syndrome is the kidney disease. In this paper, we will briefly review the epidemiology of ADPKD, conventional and novel biomarkers which may be useful in following the disease process, and prevention and treatment strategies

The Forgotten Role of Central Volume in Low Frequency Oscillations of Heart Rate Variability

The hypothesis that central volume plays a key role in the source of low frequency (LF) oscillations of heart rate variability (HRV) was tested in a population of end stage renal disease patients undergoing conventional hemodialysis (HD) treatment, and thus subject to large fluid shifts and sympathetic activation. Fluid overload (FO) in 58 chronic HD patients was assessed by whole body bioimpedance measurements before the midweek HD session. Heart Rate Variability (HRV) was measured using 24-hour Holter electrocardiogram recordings starting before the same HD treatment. Time domain and frequency domain analyses were performed on HRV signals. Patients were retrospectively classified in three groups according to tertiles of FO normalized to the extracellular water (FO/ECW%). These groups were also compared after stratification by diabetes mellitus. Patients with the low to medium hydration status before the treatment (i.e. 1st and 2nd FO/ECW% tertiles) showed a significant increase in LF power during last 30 min of HD compared to dialysis begin, while no significant change in LF power was seen in the third group (i.e. those with high pre-treatment hydration values). In conclusion, several mechanisms can generate LF oscillations in the cardiovascular system, including baroreflex feedback loops and central oscillators. However, the current results emphasize the role played by the central volume in determining the power of LF oscillations

Effectiveness of polymyxin B-immobilized fiber column in sepsis: a systematic review

INTRODUCTION: Severe sepsis and septic shock are common problems in the intensive care unit and carry a high mortality. Endotoxin, one of the principal components on the outer membrane of gram-negative bacteria, is considered important to their pathogenesis. Polymyxin B bound and immobilized to polystyrene fibers (PMX-F) is a medical device that aims to remove circulating endotoxin by adsorption, theoretically preventing the progression of the biological cascade of sepsis. We performed a systematic review to describe the effect in septic patients of direct hemoperfusion with PMX-F on outcomes of blood pressure, use of vasoactive drugs, oxygenation, and mortality reported in published studies. METHODS: We searched PubMed, the Cochrane Collaboration Database, and bibliographies of retrieved articles and consulted with experts to identify relevant studies. Prospective and retrospective observational studies, pre- and post-intervention design, and randomized controlled trials were included. Three authors reviewed all citations. We identified a total of 28 publications - 9 randomized controlled trials, 7 non-randomized parallel studies, and 12 pre-post design studies - that reported at least one of the specified outcome measures (pooled sample size, 1,425 patients: 978 PMX-F and 447 conventional medical therapy). RESULTS: Overall, mean arterial pressure (MAP) increased by 19 mm Hg (95% confidence interval [CI], 15 to 22 mm Hg; p < 0.001), representing a 26% mean increase in MAP (range, 14% to 42%), whereas dopamine/dobutamine dose decreased by 1.8 microg/kg per minute (95% CI, 0.4 to 3.3 microg/kg per minute; p = 0.01) after PMX-F. There was significant intertrial heterogeneity for these outcomes (p < 0.001), which became non-significant when analysis was stratified for baseline MAP. The mean arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio increased by 32 units (95% CI, 23 to 41 units; p < 0.001). PMX-F therapy was associated with significantly lower mortality risk (risk ratio, 0.53; 95% CI, 0.43 to 0.65). The trials assessed had suboptimal method quality. CONCLUSION: Based on this critical review of the published literature, direct hemoperfusion with PMX-F appears to have favorable effects on MAP, dopamine use, PaO2/FiO2 ratio, and mortality. However, publication bias and lack of blinding need to be considered. These findings support the need for further rigorous study of this therapy

Volume Assessment in Mechanically Ventilated Critical Care Patients Using Bioimpedance Vectorial Analysis, Brain Natriuretic Peptide, and Central Venous Pressure

Purpose. Strategies for volume assessment of critically ill patients are limited, yet early goal-directed therapy improves outcomes. Central venous pressure (CVP), Bioimpedance Vectorial Analysis (BIVA), and brain natriuretic peptide (BNP) are potentially useful tools. We studied the utility of these measures, alone and in combination, to predict changing oxygenation. Methods. Thirty-four mechanically ventilated patients, 26 of whom had data beyond the first study day, were studied. Relationships were assessed between CVP, BIVA, BNP, and oxygenation index (O2I) in a cross-sectional (baseline) and longitudinal fashion using both univariate and multivariable modeling. Results. At baseline, CVP and O2I were positively correlated (R = 0.39; P = .021), while CVP and BIVA were weakly correlated (R = −0.38; P = .025). The association between slopes of variables over time was negligible, with the exception of BNP, whose slope was correlated with O2I (R = 0.40; P = .044). Comparing tertiles of CVP, BIVA, and BNP slopes with the slope of O2I revealed only modest agreement between BNP and O2I (kappa = 0.25; P = .067). In a regression model, only BNP was significantly associated with O2I; however, this was strengthened by including CVP in the model. Conclusions. BNP seems to be a valuable noninvasive measure of volume status in critical care and should be assessed in a prospective manner